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Drilling in antiquity ..... did you know the Ancient Egyptians
used drilling techniques in the construction of the pyramids
from 2550 BC?
The Chinese used a technique, known as Spring Pole Drilling,
involving the repetitive lifting, dropping and rotating of
coupled bamboo rods to drill holes of up to 100 metres.
It is believed that using this method, drillers would work
for days to penetrate just half a metre through the rock.
Rapid development of drilling methods and equipment occurred
during the nineteenth century.
Manual drilling techniques, such as "Hammer and Taper"
- where one man would hold the sharpened drill steel while
two others would hit the end with a sledge hammer - soon
gave way to motorised drills. Steam, electricity or compressed
air was used to power these modern drills allowing drilling
to greater depths and at much faster rates.
Drilling is also used to obtain rock samples from below
the surface, providing vital information in the identification
of resources and planning the development of a mine.
There are four main types of exploration drilling techniques:
• RAB (Rotary Air Blast): This is the cheapest and least penetrative
type of drilling.
• AIR CORE: One of the cheaper forms of drilling, less likely to provide
contaminated samples than RAB drilling.
• RC (Reverse Circulation): More expensive drilling technique, able
to drill 500 m below the surface.
• Diamond Drilling: This is the most expensive drilling technique,
allowing greatest penetration and recovery of whole cores of rock, providing
the best indication of mineralisation patterns.
Commonly called mechanical boggers, compressed air powered
loader were introduced to the Eastern Goldfields at the end
of the 1920s.
They stood on rails which could be progressively extended
forward as the rock in front was removed.
After a shovel full was picked up, the ore was transferred
straight back over the top of the loader and into an ore
borrow drawn up behind.
This allowed them to work in quite narrow spaces, but that
was also the most dangerous situation for the operator who
stood beside the machine to handle the controls and who could
easily be crushed if it tipped over sideways whilst in operation.
Such incidents were not uncommon.
The ore was then transported on the borrows through the
tunnels, dipped into vertical shafts and at their end collected
in large buckets that were winched up to the surface.
The ore was then transported to the State Battery.
At State Batteries the hard-won ore was crushed.
Foundries as far away as London churned out dozens - no,
hundreds - of these early processing plants.
Most had either ten or twenty "heads" though some
had as many as forty.
Multiples of five ensured that intervals of raising each
stamp-head could be carefully set to establish a balancing
rhythm to the battery's operation.
This type of ball mill was commonly used for dry crushing
ore on the Golden Mile in the years before World War I, but
thereafter wet milling types gained preference.
The crushing drum carried a charge of loose steel balls and
is lined with an arrangement of hardened steel plates, overlapped
to create a stepped profile which increases the crushing
and grinding effect of the steel balls as the drum rotates.
Ore is continuously fed into the drum through a chute entering
on its axis and when finely enough ground, passes out underneath
through screens.
Pans like these were once commonly used by mining companies
and State Batteries to extract gold from other material by
mercury amalgamation.
Mercury has an affinity for gold and for some other
metals.
Upon contact, it will unite with clean free particles of
them and form an amalgam which can easily be treated to obtain
gold.
Part filled with gold bearing material and a quantity of
mercury, the pans rotated so that steel balls or contoured
plates would crush the material, liberating the gold.
A regulated flow of water into the pan and overflowing out
of it carried away the finely ground depleted material but
not the amalgam which, because of its density, remained on
or near the bottom of the pan.
The mercury was later removed by roasting.
An interesting display is the explosives magazine.
In 1894 explosives were shipped from the icy factory, Nobles
Explosives Company in Scotland, unloaded in Fremantle and
then transported to Kalgoorlie by camel train or horse drawn
wagons.
The transport from the factory to the mine took 4 - 6 months.
An explosives magazine was constructed in Kalgoorlie to
prevent theft and to keep the explosives cool and dry.
The building had an outer and inner skin with vents to the
interior. As the sun heated the roof, cool air was drawn
from under the building into the ventilation system.
There were no windows build for the sunlight to enter and
artificial lighting was strictly prohibited.
Only the magazine keeper had keys and nobody entered the
magazine without him.
The explosives were moulded to Dynamite cartridges first
by hand later on by machine.
Today the explosives are made at the mine and delivered immediately
into the blastholes.
The next interesting stop is the National Bank of Australasia
Ltd (now the National Australia Bank Limited ).
Although it was the largest bank in Western Australia when
the 1890s gold boom began, the National Bank shunned the
risk of opening branches in the goldfields.
Finally in August 1894 it had to open branches in Coolgardie
and Kalgoorlie, to protect its mercantile connections in
Perth and Fremantle.
The reasons for restraint was the debt being carried on the
Midland Railway, which was one of the most worrying transactions
in the bank's early history as it was forced to carry £150'000
debt for the project for many years.
Also a worry was the eastern states recession, which saw
a number of banking institutions crash and severely reduced
business for those that survived.
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